S29: Induction of biofilm dispersion by the communication molecule, cis-2-decenoic acid

Recently our laboratory reported the discovery of a novel cell-to-cell signaling system used by Pseudomonas aeruginosa to induce biofilm dispersion in a cell density-dependent manner.  At present, this is the only known dedicated communication system responsible for inducing natural dispersion of microbial biofilms.  The inducer in this system, cis-2-decenoic acid is a small messenger fatty acid which is structurally related to Diffusible Signal Factor (DSF) of Xanthomonas and Xylella species, where it regulates virulence in these organisms.  When present in a system, cis-2-decenoic acid is able to inhibit the formation of biofilms and when added to developed biofilms it is able to induce these to disperse and enhance the activity of a wide range of antimicrobial agents including oxidizing and non-oxidizing biocides as well as antibiotics.  Results from tests using cis-2-decenoic acid against Pseudomonas aeruginosa biofilms demonstrated an increase in cidal activity of anti-bacterial agents ranging from 0.5 log to over 5 log.  The adjunctive property of cis-2-decenoic acid is a consequence of inducing a transition from a biofilm state, to a planktonic state in the bacteria tested. Antibiotic activity against a range of gram-postive and gram-negative bacteria and Candida has also been shown to be significantly enhanced when treatment is combined with the addition of cis-2-decenoic acid.  These results demonstrate that cis-2-decenoic acid shows significant promise as an agent for the control of the growth and persistence of microbial biofilms and may be a harbinger of a new range of “greener” antimicrobial treatments in the future.